Primate auditory cortex is composed of areas grouped in regions at 3 levels in a hierarchical order of core-belt- parabelt, and each region subdivides into multiple areas. Auditory information processing proceeds through levels and through areas within every level. Information in belt and parabelt regions diverges into parietal (dorsal) and temporal lobe (ventral), both of which ultimately target different regions of prefrontl cortex. Gathering evidence indicates that auditory information representation becomes more complex and abstract as the processing advances. This project focuses on the properties of the parabelt (PB) region on the superior temporal gyrus (STG) in macaque monkeys for two reasons. First, while PB is fairly well defined anatomically in monkeys (e.g. it divides into cauda and rostral areas, CPB and RPB, respectively), the location and extent of the human PB is less clear because it has been variably defined by different technical criteria. Characterizing the functional properties of the macaque PB may help in better-defining the human PB. Second, while human STG has been implicated in various functions particularly related to perception of communication signals like speech, the physiological properties of macaque PB have not been systematically studied, primarily due to the technical difficulties of accessing the macaque STG. Thus, the detailed auditory physiology of the macaque PB holds some of the key information missing in our understanding of the organization and functioning of the primate auditory cortex. Our BROAD OBJECTIVE is to characterize the physiological properties, functions and organizations of the PB areas in primates. As PB areas are widely regarded as task-sensitive, we will record PB activity in monkeys performing sensory tasks that entail active discrimination of the test stimuli. SPECIFIC AIM 1 is to systematically characterize acoustic preferences (e.g. spectral and temporal tuning) of the PB neurons by examine their responsiveness to a battery of auditory stimuli. This will provide the first ever detailed survey of basic PB physiology. SPECIFIC AIM 2 is to characterize communication signal processing in PB. We examine neural responses to conspecific vocalization while manipulating their sensory modality or intelligibility and relate these responses to behavioral performance. Both AIMs also allow comparisons of CPB and RPB, to provide more details about PB organization. SPECIFIC AIM 3 is to investigate the network architecture of PB by exploring the connection patterns of PB anatomically and neurophysiologically. This will help understand how PB areas interact to process information and pass it to the next levels. Several communication disorders (e.g. autism) implicate STG or higher level of auditory systems for its impaired functionality. Basic properties of STG (PB areas in the case of monkeys) are essential for understanding these, as well as basic sensory impairments.